1. Field of Invention
The present invention relates to a non-destructive X-ray inspection apparatus for the food industry, particularly for glass vessels and/or metal cans.
2. Brief Description of the Prior Art
It is known that, in the vast majority of cases, non-destructive X-ray inspection of glass vessels in food industry applications is carried out by single devices, located on one side of the row of said vessels to be inspected; said devices being substantially equipped with an emitter and a sensor between which the row of said vessels to be inspected moves.
Similarly known is the fact that with such single devices a 90-95% inspection is obtained of the product contained therein, said deficiency being due to the shadow area projected by the concavity that is present, more or less importantly, in the vessel bottom.
To be more precise, refer to a glass vessel containing jam or a similar product; the impairing concavity is the one on the bottom of these vessels; this projection overlaps the contaminating agents hiding them and making their recognition impossible.
In many cases this result has been deemed, wrongly, enough, because an inspection valid only at 95% created a lot of problems, which it was attempted to solve through a few solutions, that proved, however, rather complicated and costly and not satisfactory enough.
Among the above solutions, mention can be made of a 45.degree. slant on the vertical emitter pipe plan. This solution, however, only generated another shadow area in another point with respect to the traditional inspection apparatus placed on one side. Moreover, though mitigating the darkening, it did not solve the problem (which is often due to high vessel tolerances). Furthermore, it cannot be applied to cans.
Another solution being studied in the United Kingdom provides two inspection apparatus mutually placed at 90.degree. on the vertical plan.
This latter solution seems to benefit from a partial reduction of shadow areas, but it uses two inspection apparatus and the system overall dimensions are rather big; the cost for the two apparatus, their maintenance and the like are important cost elements that cannot be overlooked.
Other prior attempts to deal with the problems associated with inspection of contents include arrangements where the X-ray radiation from a source is altered or intensified, before being detected. The intensification of X-ray radiation, however, can bring about image distortion in the upper portion of a jar. An X-ray inspection technique has been used in U.S. Pat. No. 3,958,078 "X-Ray Inspection Method and Apparatus" which employs a brightness intensifier to modify X-ray radiation which is then viewed by a camera.
Another U.S. Pat. No. 4,064,440 "X-Ray or Gamma Ray Examination Device for Moving Objects" employs a bank of adjacent detectors arranged in an array. The "Method and Apparatus for Examining the Content of Containers" disclosed in U.S. Pat. No. 4,566,113 provides a method for ascertaining the weight of container contents with an X-Ray technique. A "Measuring and Controlling System" which uses X-Ray radiation for controlling the height of material deposited into a container by an automatic dispensing machine is disclosed in U.S. Pat. No. 3,007,048.
A need still exists for a solution which is economical and accurately able to inspect vessels with the problem of the shadowed or hidden areas being addressed.